Insects face many cognitive challenges as they navigate nutritional landscapes that comprise their foraging environments with potential food items. The emerging field of nutritional geometry (NG) can help visualize these challenges, as well as the foraging solutions exhibited by insects. Social insect species must also make these decisions while integrating social information (e.g., provisioning kin) and/or offsetting nutrients provisioned to, or received from unrelated mutualists. In this review, we extend the logic of NG to make predictions about how cognitive challenges ramify across these social dimensions. Focusing on ants, we outline NG predictions in terms of fundamental and realized nutritional niches, considering when ants interact with related nestmates and unrelated bacterial, fungal, plant, and insect mutualists. The nutritional landscape framework we propose provides new avenues for hypothesis testing and for integrating cognition research with broader eco-evolutionary principles.

The evolution of symbiotic interactions may be affected by unpredictable conditions. However, a link between prevalence of symbiosis and these conditions has not been widely demonstrated. We test for these associations usingDictyostelium discoideumsocial amoebae and their bacterial symbionts.D. discoideumare host to endosymbiotic bacteria from three taxa:Paraburkholderia,Amoebophilusand Chlamydiae. Three species of facultativeParaburkholderiasymbionts are the best studied and give hosts the ability to carry food bacteria through the dispersal stage to new environments.Amoebophilusand Chlamydiae are obligate endosymbionts with no measurable impact on host fitness. We test whether the frequency of both single infections and coinfections of these symbionts are associated with the unpredictability of their soil environments by using symbiont presence-absence data from soil isolates from 21 locations across the eastern United States. We find that thatAmoebophilusand Chlamydiae obligate endosymbionts and coinfections are not associated with any of our mean measures, but that unpredictable precipitation can promote or hinder symbiosis depending on the species ofParaburkholderiasymbiont.